Probability Distributions of Random Electromagnetic Fields in the Presence of a Semi-Infinite Isotropic Medium

Using a TE/TM decomposition for an angular plane-wave spectrum of free random electromagnetic waves and matched boundary conditions, we derive the probability density function for the energy density of the vector electric field in the presence of a semi-infinite isotropic medium. The theoretical analysis is illustrated with calculations and results for good electric conductors and for a lossless dielectric half-space. The influence of the permittivity and conductivity on the intensity, random polarization, statistical distribution and standard deviation of the field is investigated, both for incident plus reflected fields and for refracted fields. External refraction is found to result in compression of the fluctuations of the random field.Comment: 23 pages, 11 figures, accepted for publication in Radio Scienc

Africa's media: democracy and the politics of belonging

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Probability Distribution of the Quality Factor of a Mode-Stirred Reverberation Chamber

We derive a probability distribution, confidence intervals and statistics of the quality (Q) factor of an arbitrarily shaped mode-stirred reverberation chamber, based on ensemble distributions of the idealized random cavity field with assumed perfect stir efficiency. It is shown that Q exhibits a Fisher-Snedecor F-distribution whose degrees of freedom are governed by the number of simultaneously excited cavity modes per stir state. The most probable value of Q is between a fraction 2/9 and 1 of its mean value, and between a fraction 4/9 and 1 of its asymptotic (composite Q) value. The arithmetic mean value is found to always exceed the values of all other theoretical metrics for centrality of Q. For a rectangular cavity, we retrieve the known asymptotic Q in the limit of highly overmoded regime.Comment: accepted for publication in IEEE Trans. Electromagn. Compat., 201

An active wearable dual-band antenna for GPS and Iridium satellite phone deployed in a rescue worker garment

An active wearable dual-band circularly polarized microstrip patch antenna for Global Positioning System and Iridium satellite phone applications is presented. It is constructed using flexible foam and fabric substrates, combined with copper-on-polyimide film conductors. A low-noise amplifier chip is integrated directly underneath the antenna patch. The antenna's performance is examined under bending and on-body conditions. The active antenna gain is higher than 25 dBi and the 3dB axial ratio bandwidth exceeds 183 MHz in free-space conditions. The antenna performance is robust to bending and on-body placement

Marching the nation: an essay on the mobility of belonging among militant youngsters in Côte d’Ivoire

This programmatic paper seeks to develop a new perspective on the military-political identity and performance of militias particularly in urban environments. The militia under consideration is the Groupement Patriotique pour la Paix (GPP), one of the oldest and most prominent of the southern militias. The GPP came into being as a civil society initiative in the aftermath of the September 2002 insurgency in Côte d’Ivoire a country which since then has lingered in a no-peace-no-war situation. The new perspective, here called ‘ludus pro patria’, looks at how the militias’ activity, organisation, and discourse is deployed in the urban public sphere and to what effect. Within the scope of this paper, this perspective serves to deconstruct the alleged process of ‘milicianisation’ as the combined effect of discursive appropriation and concrete insinuation of a subaltern youth initiative by national elites and international actors. In conclusion, this paper argues that the proposed approach is essential for a proper understanding of two main dimensions of the militias’ raison d’être and modus operandi: mobility and belonging

MEDIATING MATONGE: RELOCATIONS OF BELGIAN POSTCOLONIALITY IN FOUR FILMS

In this paper I look at the Matonge neighbourhood of Brussels as a locus of postcolonial and diasporic imagination and activism by different groups and individuals most notably people who identify as Africans, Belgians with African roots, or ‘Black’ in Belgium. Within a longer historical narrative that starts in the late 19th century, I focus on the period beginning in the late 1980s when new migrational flows from Africa and other southern countries into Brussels make the Matonge quarter increasingly visible in an otherwise hesitantly globalizing Belgian/European metropolis. This issue is taken up by several filmmakers who, over the last thirty years, have situated their critiques of the Belgian postcolonial condition in ‘Matonge’. In this paper I briefly present four of these films in order to illustrate the ways in which ‘Matonge’ features in changing discourses concerning inequality, cultural affirmation, and diasporic activism

Belgian memories, African objects: colonial re-collections at the Musée africain de Namur

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